Biology 5090/62 — October/November 2010
Cambridge O-Level · Alternative to Practical · worked solutions for every part, with the mark scheme
Topics Experimental Contexts · Microscopy and Biological Drawing · Observations and Measurements · Use of Techniques, Apparatus and Materials · Analysis, Conclusions and Evaluation · Planning Experiments and Investigations
Fig. 1.1 shows the apparatus used in an investigation for measuring the rate of water uptake as a way of comparing transpiration rates.
- The plant is attached to the glass tube by a short piece of rubber tube.
- This is carried out under water so that no air can enter the base of the plant.
- As the plant absorbs water it draws more water along the capillary tube.
- It is noted how far along the scale the water moves in two minutes.
- Water can be added from the syringe to refill the capillary tube.
- This is recorded in Table 1.1.
- Readings were taken at intervals of two hours, as shown in Table 1.1.
Table 1.1
| time of day reading taken | distance moved in two minutes / arbitrary units |
|---|---|
| 0800 | 7 |
| 1000 | 12 |
| 1200 | 26 |
| 1400 | 29 |
| 1600 | 42 |
| 1800 | 30 |
| 2000 |
Complete Table 1.1 by reading the scale in Fig. 1.1.
State how the scale could be set to zero before another reading was taken.
______
Construct a graph from the figures in Table 1.1.
Suggest three named environmental conditions that might account for the shape of the curve.
- ______
- ______
- ______
Suggest a possible reason for the reading at 1400 hours being lower than might have been expected.
______
Fig. 1.2 represents a section through a leaf.
Draw arrows and labels on Fig. 1.2 to show:
a pathway by which water moves through the leaf and is lost to the atmosphere.
Identify, using appropriate labels, the physical processes that are involved.
the route taken by carbon dioxide that is being used in photosynthesis.
Label the leaf cells that are important in these processes.
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